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How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 3:27 am
by aznetcowboy
I have been noticing that the forecast images sure don't match up with the weather in my area. Like tonight, it is forecasting "Stormy with much precipitation". Not a chance of it!
It was very dry here with a temperature of 84 today and will be about 82 tomorrow and dry. Not a chance of any precipitation until this coming Friday. Until then we are expecting what we call chamber of commerce weather.
So, how does Cumulus come up with these forecasts?
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 4:20 am
by beteljuice
Compred to other sources your Pressure seems a bit low.
Have you set your relative (sea level) correctly ?
ATM you have 29.15 inHg, 'the web' says 30.15 inHg
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 4:36 am
by aznetcowboy
beteljuice wrote:Compred to other sources your Pressure seems a bit low.
Have you set your relative (sea level) correctly ?
ATM you have 29.15 inHg, 'the web' says 30.15 inHg
Okay, now I have to publicly display my total ignorance. Where do I make this adjustment? I have been looking through the different configuration pages and don't see a place to do that. I know, it is probably as obvious as the nose on my face, but I am still somehow missing it.
Or is that it in the calibration page? If so, how do I have any idea what adjustment I need to make?
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 5:50 am
by beteljuice
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 9:35 am
by steve
Are you getting "Exceptional weather" that? If so, have you looked in the FAQ?
http://wiki.sandaysoft.com/a/FAQ#My_for ... itation.22
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 4:29 pm
by aznetcowboy
No, not exceptional weather, just "Stormy with much precipitation". Maybe for this coming weekend (if the TV weather people are correct). I have the pressure setting as 29.00 for the low and 31.00 for the high. Too extreme?
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 4:47 pm
by steve
Given that your pressure was apparently reading too low to begin with (as suggested by beteljuice above), yes. It's quite close to your lower threshold, hence the forecast.
Re: How does Cumulus come up with these forecasts?
Posted: Sun 03 Mar 2013 11:30 pm
by beteljuice
I have the pressure setting as 29.00 for the low and 31.00 for the high. Too extreme?
Why did you change them ?
The 'forecast' setting range should be 950 mb (28.05 inHg) > 1050 mb (31.01 inHg)
Use the correct figures for whichever unit you have checked - this unit is INDEPENDENT of the unit chosen for the Cumulus station settings and is ONLY used for the Zambretti forecast.
... but ...It all means nothing if you have correctly set your station Relative pressure.
Further, the figures you want to send to other sources are unreliable and may be rejected by some places who do a safety check against stations in same locality.
Re: How does Cumulus come up with these forecasts?
Posted: Mon 04 Mar 2013 12:30 am
by aznetcowboy
beteljuice wrote:Why did you change them ?
The 'forecast' setting range should be 950 mb (28.05 inHg) > 1050 mb (31.01 inHg)
Well, it sure seemed like the range I had was not correct, so I made a change. I can do this range, no problem. I was finally able to get a good pressure reading from our airport, so I was able then to adjust the pressure in the configuration page. Now it seems much better. Our weather today has been very changeable, and I seem to be do quite well at the moment.
According to the forecasts, it will be an interesting week with even snow possible by the weekend, but I won't be home for about a week, so I won't know how well the Cumulus forecast will be. But it will be cold no matter what.
Re: How does Cumulus come up with these forecasts?
Posted: Mon 04 Mar 2013 12:59 am
by beteljuice
adjust the pressure in the configuration page.
It's your weather station that needs to be 'set', not Cumulus.
Re: How does Cumulus come up with these forecasts?
Posted: Mon 04 Mar 2013 3:55 am
by aznetcowboy
beteljuice wrote:adjust the pressure in the configuration page.
It's your weather station that needs to be 'set', not Cumulus.
Understood and it has been done. All seems okay right now. This week will be a good test of it going from the 80's and sunny to the 40's with precipitation in just 6 days. Who was it that said the weather in the high desert was boring. Oh yes, it was me.
Re: How does Cumulus come up with these forecasts?
Posted: Mon 04 Mar 2013 4:36 am
by beteljuice
Hopefully your forecast (and your dew point, etc.) will now be more realistic
Re: How does Cumulus come up with these forecasts?
Posted: Tue 05 Mar 2013 4:21 pm
by aznetcowboy
beteljuice wrote:Hopefully your forecast (and your dew point, etc.) will now be more realistic
I've been comparing them against the NWS location at the Tucson International Airport, which is the official readings for here. So far, any errors are what would be expected from their location about 12 miles at the crow flies. We are about 700 feet higher and not as a desert environment as they are. I am convinced my readings are accurate for my location.
Thanks for the assistance you gave me in resolving my problem.
